Transmitter



May 13, 1930. CIRELL] 1,758,650

TRANSMITTER Filed Aug. 4, 1928 2 Sheets-Sheet 1 WI TNE'SSES INVENTOR.

MW l 'Ii'aflcesco Lz'relli a I W ATTORNEY.

May 13, 1930. F. CIRELLI I 1,758,650

TRANSMITTER Filed Aug. 4, 1928 2 Sheets-Sheet 2 INVENTOR: fianaesco 65132117,

v ATTORNEY.

Patented May 13, 1930 TED STATES FRANCESCO GIRELLI, 0F PHILADELPHIA, PENNSYLVANIA TRANSMITTER Application filed August 4, 1928. Serial No. 297,539.

My invention relates to transmitters of the type which, under the influence of sound waves, cause electric currents to flow.

The object of the invention is to provide a transmitter. which may be connected to a phonograph or the like and electrically connected to an amplifier, such as the amplifier of a radio receiver, so that sound produced by the phonograph may be reproduced by the amplifier.

In its preferred form, my improved transmitter consists of one or more microphones mounted in a casing, which may be connected between the tone arm and the sound box of the phonograph without alteration thereof, and provided with electric conductors which may be connected to an amplifier, as illustrated by the embodiment shown in the accompanying drawings in which,

Figure 1 is a longitudinal section through a transmitter made in accordance with my invention,

Figure 2, a cross-section therethrough, taken on line 22 on Figure 1,

Figure 3 a fragmentary plan view of a phonograph on which one of my transmitters has been mounted, certain parts being broken away, and 1 Figure 4 a front view of a radio receiver, shown electrically connected to the transmitter illustrated in'Figure 3.

Referring more in detail to the drawings, the transmitter is preferably provided with a casing consisting of a sleeve 10 and conplings 11 and 12 which may have a forcedfiton the ends of the sleeve to provide easy and economical assembly. A microphone support, consisting of an outer cylinder 13 and an inner cylinder 14, is mounted in sleeve 10 and held against axial movement by clips 15 secured to the outer cylinder and having one end of each bent outwardly and extending between the end of the sleeve and a shoulder 16 formed on coupling 11. The outer cylinder is preferabl hreaded onto the inner cylinder in order that the microphone support mag be adjustable as to length.

pair of microphone 17 are mounted in the microphone support in contact with one another. Each of the microphones shown has a two-piece shell 18 containing granulated carbon 19 which is retained therein by a diaphragm 20 carrying an electrode 21. As these microphones are well known they will not be further described. Resilient fingers 22, preferably made of thin spring metal, are secured to each shell 18 and engage flanges 23 and 24 formed on cylinders 13 and 14 respectively, the ends of clips 15 being shown bent against flange 13.

In assembling the transmitter, a microphone is placed inside cylinder 13 with its fingers resting against flange 23, a second microphone placed against the first one and cylinder 14 screwed into cylinder 13 until flange 24 engages the fingers on the second microphone. The microphone support is then inserted in sleeve 10 and a pair of electric conductors 25 and 26 passed through apertures in the side walls of sleeve 10 and cylinder 13 and connected to electrodes 21. Couplings 11 and 12 are forced onto the ends of the sleeve with shoulder 16 engaging clips 15 and holding the support against axial movement while fingers 22 hold the microphones against transverse movement.

As shown in F igures 3 and 4, coupling 11 may be inserted in the tone arm 28 of a phono graph 29, a sound box 30 inserted into the end of coupling 12, and conductors 25 and 26 connected to an amplifier, such as the amplifier of the radio receiver 27. As the stylus of the sound box travels around the groove in the record 31, the sound waves produced by the diaphragm of the sound box will impinge against the diaphragms of the microphones and permit electric currents to flow through conductors 25 and 26 so that the amplifier of receiver 27 may reproduce the same sounds simultaneously with the amplifier of the phonograph.

The transmitter will operate efliciently if equipped with but one microphone but, in practice, I find that by' installing two microphones in the transmitter, speeches and music arereproduced with greater faithfulness and clarity of tone.

While I have illustrated and described a certain embodiment of my invention, it is understood that modifications may be made without departing from the spirit thereof and, hence, I do not wish-to limit myself to the precise construction set forth but consider that I am at liberty to make such changes, alterations and applications as fairly come within the scope of the appended claims.

I claim:

1. A transmitter including a microphone having a shell and an electrode, a casing surrounding the microphone and adapted to be inserted between the sound box and the tone arm of a phonograph, a flange in the casing, resilient fingers secured to the shell and engaging the flange, and electrical conductors electrically connected to the shell and the electrode.

2. A transmitter including a sleeve, ouplings on the ends of the sleeve for con ection to the sound box and the tone arm of a phonograph, a microphone support in the sleeve, a microphone mounted in the support and having a shell and an electrode, resilient fingers secured to the shell and engaging the support, and electrical conductors connected to the shell and the electrode.

3. A transmitter including a casing, a microphone support in the casing, a-pair of microphones mounted in the support contacting with each other, and provided with electrodes, and electrical conductors connected to the electrodes, said support being comprised of parts telesco ically adjustable, one of said microphones eing mounted in each part.

4. A transmitterincluding a sleeve, couplings on the ends of the sleeve for connection to the sound box and the tone arm of a phonograph, an outer cylinder in the sleeve, clips on the cylinder secured between a coupling and one end of the sleeve, an inner cylinder threaded into the outer cylinder, flanges on the ends of the cylinders, a pair of microphones mounted in the cylinders, abutting each other and provided with electrodes, resilient fingers secured to the microphones and abutting the flanges, and electrical conductors connected to the electrodes.

In testimony whereof I have signed my name to this specification.

FRANCESCO CIR'ELLI. 

